Electron gun and the like



H. M. GAUN ETAL ELEGTRON GUN AND THE LIKE oct. 16, 1945.

Filed Nov. 29, 1944 4 Sheets-Sheet 1 Vvvwvwwv ATTORN EY Oct. 16, 1945.H. M. GAUN ET AL 2,386,790

ELECTRON GUN AND THE LIKE Filed Nov. 29, 1944 4 Sheets-Sheet 2 INVENTORS571ML j@ ATTORNEY Oct. 16, 1945. H. M. GAUN ET AL 2,386,790

ELECTRON GUNAND THE LIKE Filed Nov. 29, 1944 4 Sheets-Sheet 3 ATTORN EYAoet. 16, 194s.

H. M. GAUN ET AL ELEcTRoN GUN AND THE LIKE Filed Nov. 29, 1944 l4sheets-sheet 4 HWI. ""lllih' YWI..

INVENTORS ATTORNEY Paten-ad oci. 16, 194s 2,380,790 monton GUN AND 'mauna Harry M. Gann and Ross K. Cessioni, limporiuua x Pa., assigner: toSylvania Electric Products va corporation of Musa- Ino., Emporium, Pachusetts Application November zo, 1944, serial Nassasez s claims. (ci.25o-21.5)

'I'his invention refers to electron guns as employed for the developmentand focusing of electron beams in cathode ray tubes and similar electrondischarge devices. and more particularly to the cathode-grid unit ofelectron guns.

It is a principal object of the invention to provide an improvedassembly unit' consisting of cathode, grid, heater and co-ordin'atedauxiliary members which can -be precisely and uniformly spaced andrigidly and permanently attached to each other by simple operations.

'I'he type of electron gun withlwhich this invention is concernedcomprises a cylindrical cathode sleeve into which a heater coil isinserted from one end and which is closed at its other end by a ilatmetal cap covered wth a thermionic electron emitting coating from whichelectrons are drawn in substantially axial direction by an axiallysymmetrical electric field which penetrates through a small centralaperture in a disk shaped control electrode or grid mounted in axiallyspaced relation to the cathode cap and in close proximity to it. Thegrid or aperture disk forms the end surface of a cylindrical metal shellco-axially surrounding the cathode sleeve. The accelerating electrode orelectrodes on the side of the grid remote from the cathode in axialdirection may consists respectively of one or more apertured disks orcylindrical electrodes, properly aligned with cathode and grid, forfocusing the electron beam at a desired axial distance. The invention isnot concerned with the accelerating electrodes, which may be connectedto the cathode-grid assembly in any known and convenient manner.

The exact spacing and permanent alignment of the 'apertured grid diskfrom the emitting flat cathode cap is very important because it deter-Imines the intensity control characteristic of the developed beam. Thiscontrol characteristic must be uniform from tube to tube. The gridalignment and spacing must, furthermore, be accurate because it formspart of the rst electron lens system by which the beam is focused andformed. Any deviation from perfect axial symmetry of the electric fieldnear the cathode will cause considerable distortion of the axialsymmetry of the developed electron beam, because the electron velocitiesare comparatively lowin this part of the gun. Because of the requiredhigh precision of the spacing and alignment of cathode and grid, and ofthe required uniformity of the close spacing of these two electrodesfrom one unit to another in the mass production of tubes of the sametype, the mechanical design of considerations of `electrical insulationand conservation of the heat supplied to the cathode by the heater. Theuse of supporting or spacing members for the cathode near the emittingend surface must be avoided, in order to prevent excessive cooling ofthat part of the cathode. The exact location of the heater unit withinthe cathode cylinder, in particular the distance between the end of theheater unit in the cathode sleeve and the thermionically emittingcathode cap, must be carefully controlled. The heater unit musttherefore be mechanically supported by and rigidly connected withawmember carry ing the cathode. y

'I'here are, generally, two methods for providing the spacing betweencathode cap and grid disk. The nrst method depends on the difference ofthe axial dimensions of the parts forming the grid cathode assembly. Inits simplest form, the

- knownprior assembly consists of three parts: a

ceramic disk with a central ho1e,tnrougn which the cathode cylinder isthreaded. At its open end the cathode is provided with an annular angewhich abuts with one sidelof the ceramic disk. and the cathode is rmlyheld in this position in the ceramic, frictionally engaging the wall ofthe hole and/or other supplementary locking means. The grid cylinder isconcentrically telescoped over the cathode and its open end held inabutting relation to the other side of the insulating disk. The distancebetween the grid disk and the cathode cap is determined by thedifference of the axial dimensions of cathode, grid,

` and the thickness of the insulator disk.

This prior known method relies on the accuracy of the xed longitudinaldimensions of the three cooperating parts. While it is useful in smallscale production, as for laboratory purposes, where the cost ofextremely high precision of the parts is immaterial, its disadvantagesfor mass production of sub-assemblies having uniform spacing from oneunit to the other are very considerable, if one considers the absolutedimensions of the spacing required for this assembly. 'I'his spacing isof the order of .020". A reasonable tolerance for the longitudinaldimensions of the component parts is of the order of .005", the greatestvariation being usually in the thickness of the insulator disks. Tosecure reasonable uniformity in quantity production, the three' partsfor each unit must be carefully matched, which is at least inconvenient,and in any event, not practical. After assembly, each unit must beinspected for spacing, e. g. by a micrometer depth gauge. During thisinspection, many units are usually found which do not conform to therequired spacing limits. It-may be mentioned in passing that in thisprior method. the heater unit 1s usually not inserted into the cathodesleeve before the grid-cathode assembly is mounted on a tube stem.

The other known method is positive,V and uses a standard spacer gaugeduring mounting. In one known procedure of this type, slots are providedat the disk end of th'e grid cylinder, through which a standard spacergauge is inserted. The cathode is telescoped concentricaliy into thegrid cylinder, until it is stopped by the spacer gauge. The assembly isthen locked together, as by welding, and the spacer gauge is withdrawnsideways from the gap between grid disk and cathode cap. That meth'odhasthe disadvantage that, in withdrawing of the spacer gauge, emittercoating may be scratched on from the cathode cap. Furthermore, the exactlocation of the openings for introducing the spacer gauge very near tothe grid disk is hard to keep within the close tolerances required forthe purpose.

Al1 these disadvantagesare eliminated by th'e present invention,according to which the parts of the assembly are so formed and mutuallyrelated to each other, that the distance between the relevant electrodeparts is continuously measurable during the telescoping of the twocylinders, by a micrometer dial gauge connected to a measuring rodpassing axially through the grid aperture, th'e point of the measuringrod being pushed along by the cathode during the telescoping motion.

'I'he invention further contemplates the provision of means forpositively locking and locating the heater unit inside the cathodesleeve, and forming a rigid heater-cathode assembly which is telescopedinto the grid cylinder as a wh'ole.

It is, therefore, another principal object of the invention to provide amethod of mounting a cathode-grid assembly in which the parts of theheater cathode section are ilrst locked together and the cathode gridspacing is carried out subsequent to th'e heater-cathode assembly,

Another object of the invention is to provide means for rigidly lockingthe flange of the cathode sleeve between two disk shaped ceramic spacersby means of two auxiliary anged metal cylinders.

A further object of the invention is to provide a separate heatersupporting disk-shaped ceramic which is provided with holes separated byshort bridge-like part of rectangular cross section, serving for rigidlysupporting and locating pairs of metal straps to which the heater endscan be easily welded.

A feature of the invention refers to the shape of one of the auxiliaryflanged metal cylinders used for clamping the two ceramic diskstogether, w'h'ereby the formation of a conducting layer on the surfaceof the insulator disk is prevented. l

Another feature of the invention refers to the shape of one of theceramic disks, which is provided with a central part of comparativelylarge thickness and a peripheral part of reduced thickness, wh'ereby acorrect seat for a centered telescoping tool during the assembly ofcathode and grid is obtained.

It is another important feature of the invention to provide meansconnecting the heater straps to the heater unit in such a manner thatthe welding operation by which the h'eater straps are conductivelyconnected to the lead-in wires in the stem of a tube does not ailect thelocation of the heater unit in th'e cathode sleeve.

Referring to the drawings which sh'ow one preferred embodiment,

Fig. 1 is an isometric, partly sectlonalized view of the finishedassembly;

Fig. 2 is a top plan-view of the lower ceramic disc with the heatersub-assembly;

Fig. 3 is a sectional view of Fia'. 2 taken along the hne 3-3 thereof;

Fig. 4 is a plan view of the cathode;

Fig. 5 is a sectional view of Fig. 4 taken along the line 5--5 th'ereof;

Fig. 6 is a top plan' view of the upper ceramic disc;

Fig. 7 is a sectional view of Fig. 6 taken along the line 1-1 thereofFig. 8 is a top plan view of one of the auxiliary cylinders for lockingthe cathode ange between the two ceramic discs;

Fig. 9 is a sectional view of Fig. 8 taken along the line 9-9 thereofFig, 10 is a top plan view of the other auxiliary metal cylinder forlocking the cathode flange;

Fig. 11 is a sectional view of Fig. 10 taken along the line thereof;

Fig. l2 is a top plan view of the completed cathode-heater sub-assembly;

Fig. 13 is a side elevational view of Fig. 12, partly sectional;

Fig. 14 is an explanatory diagram of an assembly gauge according to theinvention;

Fig. 15 is an enlarged yview of part of Fig. i4.

As can be seen in Figs. l, 35 and 13, the assembly consists of cathodesleeve I, closed at its upper end by top cap 2 and provided with aflange 3 at its open lower end; the grid cylinder 5 closed at its upperend by grid d isk 6, having a. central aperture l whose diameter isconsiderably smaller than that of cathode cap 2. The grid cylinder 5carries, on its open lower end tabs 8 and 9 disposed diametricallyopposite to each other. The assembly also includes heater coil I0 withterminal legs I| and I2, attachedto pairs of heater straps I3, I4 andl5, I6; shield cylinder I1 with upper annularly flanged shield IB;retainer ring I9 with flange 20; upper ceramic disk 2|: lower ceramicdisk 22; and cathode tab 23. The cathode tab 23 is welded to ange 3 ofcathode I.

Before describing the steps followed in the assembly of the parts,attention is called to some o! the outstanding features of the unit.Cathode I is rmly locked in position with its slightly enlarged lowerend 24 which fits tightly in hole 25 of upper ceramic 2|, and by theposition of ilange 3 between upper ceramic 2| and lower ceramic 22.Upper ceramic 2| and lower ceramic 22 are clamped together tightly bythe ilange I3 of shield cylinder Il and flange 2|) of retainer ring I9.These two members I1 and I9 are Welded together after the desired tightclamping of the two ceramic disks has been carried out. Heater coil IIIis supported by its legs and I2, which are f welded to the heater strapsI3 and I 6 respectively. The heater straps themselves are rigidlyanchored in holes provided for this purpose in lower i ceramic 22. Itwill be noted that the diameters of the two ceramic disks are equal, andthat the shield cylinder I 1 fits very tightly over the periphery ofceramic 2|. A particular advantage in aligning grid cylinder l overshield cylinder I3 l clamped together by the two auxiliary cylinders I'Iand I9, is telescoped upward into the grid cylinder. Grid cylinder litstightly overthe external cylindrical surface of shield cylinder I3,whereby a rigid, coaxial mount unit is obtained..

In describing the steps comprising the method of assembling the unit,attention is ilrst called to Figs. 2 and 3 which show top and side viewsof lower ceramic 22 having a thick central portion 23 and a thinnerperipheral portion 2'I.

Lower ceramic 22 is provided with three circular holes 28, 23 and 30arranged on a circle concentric with the external periphery of thediskshaped ceramic, and four holes 3i, 32, 33 and 34.

The parts oi the ceramic between holes 3| and 34, and between 32 and 33are recessed and form solid bridge-like portions, and are shapedrectangularly, as shown in Figs. 2 and 3. These bridgelike portions aredesignated 3l and 33 respectively.

The first step in assembling the parts is to lit heater strap I3 throughholes'li and 34, and to nt heater strap I4 from below to portion 33between holes 3i and 34. The straps I3 and I4 are then spot-weldedtogether at points 31. The same operation-is carried out with heaterstraps I5 and I3 around portion 33 between holes 32 and 33. The two legsII and I2 at the lower end of heater coil III are'now inserted i'romabove into holes 3i and 32, and the legs are welded to straps I3 and I5at points 3l. During welding of the heater legs, a length gauge or jigis preferably used to hold the heater coil in position so as to insurethe desired height of the top 33 of coil I 0 above the upper surface ofceramic 22.

The second step of mounting consists in threading cathode I from belowthrough hole oi upper ceramic 2i until cathode flange 3 touches thelower surface of ceramic 2 I. Cathode iihas a larger diameter at itslower end 24 which fits tightly into central hole 25 of top ceramic 2 ITop cap 2 extends above the upper surface of ceramic 2 I, as determinedby the thickness of the ceramic 2i. Cathode I surrounded at its lowerend ad by ceramic 2i is now telescoped over the heater assembly shown inFigs. 2 and 3, until ange 3 of cathode I is sandwiched between ceramic2l and ceramic 22. A

In threading cathode I-through hole 25, the cathode is axially orientedin such a position with respect to the ceramic 2i that cathode tab 23fits into one of the three grooves H0 at the bottom surface of ceramic2l. At the end of grooves4 lill, holes di, 52, and d3 are provided whichcan be brought to coincide with holes 28, 29 and 33 in ceramic 22. Theloose end of cathode tab 23 is inserted into one of the holes, e. g.hole 28, in ceramic 22 when the cathode Ilwith ceramic 2i is telescopedinto position with the heater-ceramic assembly. All the holes 28-33 and4I-43 are thus in registry forming a continuous passage for air duringexhaust.

The two ceramic disks, with attached heater and cathode electrodes arenow locked together by slipping shield cylinder Il from above over thetwo ceramics, and by telescoping retainer ring I9 :rom below into theopen end of shield cylinder I'I as shown in Figs. 1 and 13. The twocylinders I'I and Il 'are pushed together in axial direction as far asthey will go to clamp the two ceramic disks rigidly together. When thisposition is reached, the two cylinders are welded together at points 44and 45, and the nnished sub-unit as shown in Fig. 13 is completed.

It will be noted that shield I1 forms a roof-like shield with a centralopening, which protects the upper surface of ceramic disk 2| fromparticles which might tend to deposit on it, as by condensation' o!metal vapors developed by the cathode during its activation or duringoperation of the tube in which the assembly is iinally mounted. ShieldIl prevents, therefore, the formation of a continuous conducting surfacelayer on ceramic disk 2l which would cause cathode-t'o-grid leakage.

Another source of leakage, caused by electron emission from the heaterlegs, is prevented by the comparatively large axial dimension of lowerceramic 22, at least in its central portion 23, through which the heaterlegs I I and l2 pass. During operation, heater coil I0 is heated to ahigh temperatiue to obtain thermionic emission from the cathode. Thelegs II and I2 of heater III may become hot enough for thermionicemission, in particular near the lower end oi the coiled heater. Anyelectrons emitted from the heater legs will be completely intercepted bythe inner surface of the holes 3i and 32 in the lower ceramic 22, andare thus prevented from reaching any other electrodes or electrode leadsattached to other co-operating electrodes of a completed electron gunmount of which the present assembly forms a part.

In order to-complete the cathode-grid assembly, it is only necessary totelescope the subassembly unit of Fig. 13 into the sub-assembly unitconsisting of grid cylinder 5 and apertured grid disk 8, as shown inFig. 14. This operation is critical, because in the finished unit thedistance of cathode cap 2 from the grid disk is required to be exactwithin less than one thousandth of an inch. The actual distance being ofthe order of 10 to 20 thousandths of an inch.

According to the invention the relative axial distance between cathodecap 2 and grid disk B is continuously supervised during the time theunit of Fig. 13 is approaching its desired location in the grid,starting about 10 to 20 thousandths of an inch, before the desiredspacing is reached. The telescoping motion must therefore'be carried outvery slowly, so it can be stopped within about one thousandth of aninch. This can be carried out by controlling the relative motion of thetwo units with respect to each other with a micrometer screw if desired.A rigidly built xture is preferably provided, as shown in Fig. 14, whichis arranged to guide the two sub-assembly units into perfect axialalignment. For this purpose, the'grid unit is inserted int anappropriate grid holder 46 in which' it is rigidly held, with the griddisk pointing upward. A iixed calibrated length of the gauge pin 41 of amicrometer dial gauge is inserted into the aperture 'I from above, so`that the free lower end of the gauge pin extends a short known lengthbelow the level of grid disk 5, about double the desired iinal spacingof cap 2 to disk 6. The main body and barrel of the micrometer dialgauge "48 are rigidly supported above and axially spaced in ilxedrelation from the grid holder. A dial gauge reading is now taken.Preferably a gauge is used with an adjustable dial, so the dial read-ving canbemade zero withthepositionof the dial hand corresponding to theknown length of the lower free end of the measuring rod extendin! belowthe grid disk in this initial position.

The sub-assembly unit of Fig. 13 is now inserted into the grid cylinderfrom below, and telescoped upward until cap 2 approaches very closelybut does not touch the free lower end of the point of the measuring rodextending below the grid disk'through aperture 1. The upward motion ofthe lower unit is now continued very slowly, preferably by means of avmicrometer screw arrangement (not shown), and the -hand of the dialgauge is carefully watched. Motion of the hand on the dial gauge beginsat the instant cathode cap 2 touches the lower free end of the measuringrod 41, as, by the telescoping motion of the two units, cathode cap 2pushes the lower end point of the measuring rod upward. Telescoping iscontinued, until the dial gauge indicates that the end of the measuringrod has traveled up to the position required for the specified cathodegrid spacing. The two units are then welded together, and the completedassembly is removed from the grid holder.

Fig. 14 shows a typical guiding and spacing ilxture for carrying out thedescribed operation, and Fig. 15 illustrates a convenient method forestablishing the proper reference level for the initial depth of thefree end of the measuring rod below the grid disk.

As shown in Fig. 14, barrel 49 of the dial gauge is rigidly mounted onarm 50 of frame 5i, above arm 52 which carries grid holder 46. When gridunit is inserted into holder 46 from below, and locked into positiontherein, a. shoulder 53 of measuring rod 41 engages the annular regionof grid disk 6 adjacent to aperture, as can be more clearly seen in Fig.15. Measuring rod 41 terminates at its lower end in a thinner portion 54of smaller diameter, adapted to pass through aperture 1 withoutfriction. The length of this portion 54 is (L-l-Gi), as can be seen inFig. l5. In order to insure a positive contact between shoulder 53 ongrid disk 6 for the initial reading, the free position of the measuringrod must be so adjusted that the shoulder 53 is slightly pushed upwardwhen the grid unit is inserted, so as to yield a readable motion of hand55 on dial 48 in the initial position for obtaining a correct referencelevel reading.

The heater-cathode unit is seated in cup 56, which can be lifted in tailstock 51 by adjusting screw 56. Tail stock 51 is adapted to slide upwardalong main support 56 of frame 5I to a -xed first position into which itis locked. This fixed first position is so chosen that it telescopes theheater-cathode unit only partly into the grid unit, viz., up to a heightat which cathode cap 2 does not yet touch the lower end of portion 54 ofmeasuring rod 41. From then on, the telescoping motion is continued byslowly turning screw 58 until the desired dial reading indicates correctspacing.

The telescoping and adjusting device shown in Fig. 14 is merelyillustrative, and the invention is, of course, in no way restricted tothe application of this particular type of telescoping ilxture. Ifdesired, other gun electrodes may be mounted above and attached to gridunit, before the telescoping of the heater-cathode unit into the gridunit is carried out.

Various changes and modifications may be made in the disclosure withoutdeparting from the spirit and scope of the invention.

assenso What is claimed is:

1. An assembly unit for electron tubes of the type described, comprisinga pair of nested cylindrical electrodes, the inner electrode beingclosed at one end and in close proximity to the corresponding end oi'the outer electrode, said closed end of the inner electrode having acoating of electron-emissive material, and the adjacent end of the outerelectrode having a small central opening concentric with thelongitudinal axis oi both said electrodes, a pair of rigid insulatormembers bridged across the interior of said outer electrode, said innerelectrode having an outwardly extending annular ange at its open end theflange being sandwiched between said insulator members, and means tolock said insulator members, said flange and said outer electrodetogether as a unit.

2. An assembly unit according to claim 1 in which a heater wire istelescoped interiorly of said inner electrode and is spaced from theinner surface thereof, the free ends of said heater extending outwardlybeyond the open end of said inner electrode, and means for anchoringsaid free ends to at least one of said insulator members to maintainsaid heater in symmetrical spaced position within said inner electrode.

3. An assembly unit for electron tubes of the type described, comprisinga pair of nested cyhndrical electrodes, each of said electrodes at theadjacent upper ends having substantially ilat closure plates, theclosure plate of the outer electrode having a central opening coaxialwith the longitudinal axis of both electrodes, thelclosure plate for theinner electrode having a coating ot electron-emissive material and beingclosely adjacent to said central opening, said inner electrodehaving aflange extending radially therefrom at its lower end, a pair ofdisk-like rigid insulators between which said flange is tightlysandwiched, a pair of cylindrical metal members having inwardlyextending annular ilanges between which said insulator disks areclamped, said inner electrode, said insulator members and said pair ofcylindrical members forming a rigid unitary sub-assembly and with thecylindrical wallv of at least one of said pair of cylindrical membersrigidly fastened to said outer electrode.

4. An assembly unit according to claim 3 in which the upper one of saidinsulator disks has a central opening through which said inner electrodeclosely iits, and metallic strap means strapped around a section of thelower insulator and connected electrically to the free ends of theheater wire within said inner electrode.

5. An assembly unit according to claim 3 in which one of said pair ofcylindrical metal members has an annular extension from its said annularflange which annular extension is spaced from the insulator disks andthrough which said inner electrode centrally passes in spaced relation.

6. An indirectly heated cathode unit for electron tubes comprising atubular metal member having its upper end closed and exteriorly providedwith electron-emissive material, the lower end of said tubular metalmember being provided with a flat annular ilange extending in a planesubstantially perpendicular to the central longitudinal axis of thetubular member, a pair of disk-like ceramic members between which saidannular flange is rigidly sandwiched, a metal member having acylindrical portion closely iititing around said disk-like members andhaving a right-angle annular ange seated against the assenso vand meansto anchor the free ends of said heater to said other ceramic diskwhereby said heater is maintained in symmetrical axial relation withinsaid tubular metal member.

'1. A unitaryv electrode mount comprising a tubular cathode closed atone end by a. iiat thermionically emitting portion and provided at itsopen end with a nat annular flange; a heater unit enclosed by saidcathode and held in spaced relation to said fiat cathode portion; acup-shaped grid electrode surrounding said cathode and having a fiatapertured portion aligned with and held in axially spaced relation withrespect to said flat cathode portion; spacing and supporting meansincluding two axially aligned insulator disks between which said flatcathode iiange is tightly held; retaining meansl clamping said insulatordisks together comprising two anged metal cylinders tightly tting intoeach other and peripherally attached to said insulator disks; heatersupporting means comprising pairs of metal straps attached to one ofsaid insulator disks, and additional spacing and supporting means forthe cathode consisting of a central opening in the other one of saidinsulator disks forming a tight nt around said tubular cathode.

8. The method of mounting an electrode assembly which comprises thesteps of attaching pairs of metal straps to one of two apertured infsulator disks, said disk having a thick central portion and a thinperipheral portion, introducing the free terminals of an elongatedheater unit through two of the apertures in said insulator disk, weldingthe heater terminals to the metal straps, threading a anged cathodesleeve having anat portion on one end through a central hole in a secondinsulator disk until the flange contacts one surface of said secondinsulator disk, telescoping the cathode sleeve With the second insulatordisk attached to it over the elongated heater unit, locating thevrcathode flange closely between the two insulator disks, telescoping aiirst auxiliary anged metal cylinder over the second insulator disk,bringing its iiange in contact with the free surface of said secondinsulator disk, telescoping a second auxiliary flanged metal cylinderinto the rst auxiliary cylinder to engage with its flange the thinperipheral portion of the rst named insulator disk, welding the twoauxiliary flanged cylinders together to clamp the two insulator disksfirmly to each other, thus forming a rigid heater cathode unit,inserting said heater cathode unit into the open end of a grid cylinderclosed at its other end by an apertured disk portion, so that thetubular cathode sleeve is axially aligned with and concentricallysurrounded by the grid cylinder, inserting a xed length of the gauge pinof a micrometer dial gauge through the aperture of the grid disk,pushing the heater cathode unit further into the grid cylinder to engagethe fiat cathode end with the free end of the micrometer gauge pin, andcontinue pushing said heater-cathode assembly further into the gridcylinder until the micrometer dial indicates a desired depth of thegauge pin within the grid aperture, welding the grid cylinder to thefirstnamed auxiliary cylinder, and removing the micrometer gauge fromthe grid aperture.

HARRY M. GAUN. R. It.V GESSFORD.

